FTTH (Fiber To The Home) is the best solution for integrated access of voice, data and cable TV. FTTH access generally uses a passive optical network (PON), and an optical splitter is a core component in PON for achieving the distribution of optical signals. The optical splitter is composed of a light-splitting chip based on a planar light circuit (PLC) technology and an optical fiber array for input/output butt-coupling.
An arrayed waveguide grating (AWG) device is commonly used in the dense wavelength division multiplexing (DWDM) system, its core is the demultiplexer/multiplexer chip based on the PLC technology, and the input/output ports therein also need an optical fiber array for butt-coupling.
In large data centers, cabinets are interconnected by active optical cables (ADCs), and butt-coupling is also required for the optical fiber array, semiconductor laser array and detector array at the transceiver end of active optical cables.
Optical splitters, arrayed waveguide gratings and active optical cables may work in the harsh environment of high temperature and high humidity, thus requiring high reliability. As one of the main components, the optical fiber array shall also have a high degree of reliability.
The optical fiber array includes an optical fiber positioning substrate, a cover plate and a plurality of optical fiber ribbons. The positioning substrate is engraved with a micro-groove array of high precision for precise positioning of the optical fibers, and the optical fibers are pressed into the micro-groove by the cover plate and fixed with glue. The main factor that affects the reliability of the optical fiber array is glue de-bonding. Under the harsh environment of high temperature and high humidity, the phenomenon of de-bonding between the cover plate and the substrate occurs easily, which affects the positioning accuracy of the optical fiber and causes the failure of the device and the module.
Both the positioning substrate and the cover plate of the existing optical fiber array have a smooth optical surface, whose bonding strength with glue is not good enough. In the cross section of the optical fiber array assembly, glue filling and bonding conditions are shown in FIGS. 1 and 2. FIG. 1 and FIG. 2 are the enlarged schematic diagrams of the cross sections of a C-shaped groove positioning substrate and a V-shaped positioning substrate respectively, 10 is the end surface of the optical fiber, and 11 is the filled glue. It can be seen that all the gaps are filled and bonded with glue, but the tangential contact points between the optical fiber side and the positioning substrate or the cover plate are not bonded with glue, such as the positions 12, 13, 14 in the C-shaped groove and the positions 15, 16, 17 in the V-shaped groove. In harsh working conditions, de-bonding occurs easily in these positions, resulting in failure of the optical fiber array components.